Fix Integer-overflow in base::Time::FromExploded.

base/time/time_mac.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/time/time.h"
 
 #include <CoreFoundation/CFDate.h>
 #include <CoreFoundation/CFTimeZone.h>
 #include <mach/mach.h>
 #include <mach/mach_time.h>
@@ skipping 172 matching lines @@
   CFCalendarSetTimeZone(gregorian, time_zone);
   CFAbsoluteTime absolute_time;
   // 'S' is not defined in componentDesc in Apple documentation, but can be
   // found at http://www.opensource.apple.com/source/CF/CF-855.17/CFCalendar.c
   CFCalendarComposeAbsoluteTime(
       gregorian, &absolute_time, "yMdHmsS", exploded.year, exploded.month,
       exploded.day_of_month, exploded.hour, exploded.minute, exploded.second,
       exploded.millisecond);
   CFAbsoluteTime seconds = absolute_time + kCFAbsoluteTimeIntervalSince1970;
 
-  base::Time converted_time =
-      Time(static_cast<int64_t>(seconds * kMicrosecondsPerSecond) +
-           kWindowsEpochDeltaMicroseconds);
+  // CFAbsolutTime is typedef of double. Convert seconds to
+  // microseconds using this type and then cast to int64_t. If
+  // it cannot be suited to int64, then fail to avoid overflows.
+  CFAbsoluteTime microseconds =

[miu, 2016/10/18 19:55:13]

Even though we know CFAbsoluteTime is a double, it's not proper to use it here
because: 1) It is a data type whose timebase is in seconds; and 2) There's no
guarantee it won't be typedef'ed to something else in the future (though,
admittedly this is highly unlikely). So, please just use double here.

[maksims (do not use this acc), 2016/10/19 16:41:04]

Done.

+      (seconds * kMicrosecondsPerSecond) + kWindowsEpochDeltaMicroseconds;
+  if (microseconds > std::numeric_limits<int64_t>::max() ||
+      microseconds < std::numeric_limits<int64_t>::min()) {
+    *time = Time(0);
+    return false;
+  }
+
+  base::Time converted_time = Time(static_cast<int64_t>(microseconds));
 
   // If |exploded.day_of_month| is set to 31
   // on a 28-30 day month, it will return the first day of the next month.
   // Thus round-trip the time and compare the initial |exploded| with
   // |utc_to_exploded| time.
   base::Time::Exploded to_exploded;
   if (!is_local)
     converted_time.UTCExplode(&to_exploded);
   else
     converted_time.LocalExplode(&to_exploded);
@@ skipping 77 matching lines @@
   return Clock::MAC_MACH_ABSOLUTE_TIME;
 #endif  // defined(OS_IOS)
 }
 
 // static
 ThreadTicks ThreadTicks::Now() {
   return ThreadTicks(ComputeThreadTicks());
 }
 
 }  // namespace base